When a wireless terminal (for example, a mobile phone, a data card, or a tablet computer) communicates with a network, the wireless terminal may switch between an idle state and a connected state. To reduce electric energy consumption of the wireless terminal, when the wireless terminal is in the idle state, the wireless terminal may listen to a paging channel in a discontinuous reception DRX (Discontinuous Reception) manner. The wireless terminal wakes up at a paging occasion of each DRX period according to a standard of a location in which a serving cell lies (at this time, a wake-up period of the wireless terminal is the DRX period), and receives a paging message delivered by a network side device through the paging channel. If the received paging message does not need to be processed (for example, the paging message is sent for another wireless terminal in the same paging group), the wireless terminal goes to sleep after the paging occasion is over. If the received paging message needs to be processed (for example, the paging message is for the wireless terminal itself), the wireless terminal switches from the idle state to the connected state to process the messages. Meanwhile, a wireless terminal may also receive other messages than the paging message, for example, some control messages or a message indicating that a current paging channel is idle. FIG. 1 is a timing diagram illustrating when a wireless terminal is in the idle state.
Conventionally, methods for deciding the DRX period in various networks are different. For example, in a GSM system in China, the DRX period is usually set by a network side device to 470 ms or 940 ms; in a WCDMA system, the DRX period is usually set by a network side device to 640 ms. In a CDMA system and in an LTE system, the DRX period is usually decided by the wireless terminal, according to its service situation, through negotiation with a network side device.
It can be seen from the preceding method for deciding the DRX period that the mobile terminal cannot properly adjust the DRX period. Even if the network adopts paging retransmission during paging message delivery, that is, during delivery of the same paging message multiple times, the mobile terminal still wakes up according to the DRX period decided by the network side. This may result in unnecessary power consumption.